The use of McGrath ® Mac for awake laryngoscopy and intubation in an obese patient with a predicted diffi cult airway

Abstract

Introduction We present a case in which the McGrath® Mac videolaryngoscope was used for awake intubation. Case report An obese 38-year-old female, planned for elective surgery, was assessed to have a possible difficult airway. Awake intubation using the McGrath® Mac was planned. An antisialogogue was administered and the airway was anaesthetised. Remifentanil infusion was used for conscious sedation. Laryngoscopy was performed, which showed a Cormack and Lehane grade 1 view of the larynx. Intubation, performed without complications, was followed by the induction of anaesthesia. In the recovery, the patient reported that the intubation process was not unpleasant. Conclusion McGrath® Mac is able to facilitate awake intubation well. Introduction Awake fiberoptic intubation is the gold standard for a difficult airway. However, there are recent reports of awake intubation facilitated by videolaryngoscopes1,2. We present a case in which the McGrath® Mac (Aircraft Medical Limited, Edinburgh, UK) videolaryngoscope was used for awake intubation in an obese patient with an anticipated difficult airway. Case report The patient was a 38-year-old -female planned for elective orthopaedic surgery in an ambulatory facility within a tertiary hospital. Her medical history included obesity (body mass index 36 kgm-2, body weight 89 kg) and hypertension. Assessment of the airway indicated a possible difficult intubation–she had a receding chin and a short neck. Treatment, intervention and outcome Awake intubation using the McGrath® Mac videolaryngoscope was planned. After the application of routine monitoring, oxygen was administered via a nasal cannula. Intravenous glycopyrrolate at a dose of 0.2 mg and midazolam at a dose of 1.5 mg were administered. Lignocaine gel 2%, 10 mL was gargled and lignocaine 10% was sprayed twice on the tongue and in the hypopharynx via an atomisation device (Long Flexi Nozzle, ENT Technologies, Victoria, Australia). Remifentanil target-controlled infusion at a dose of 2 ng/mL was commenced. Verbal contact was maintained throughout. Laryngoscopy performed with minimal force and without cervical manipulation showed a Cormack and Lehane grade 1 view of the larynx. After two sprays of lignocaine 10% on the vocal cords, a 7.0 mm tracheal tube was passed through the larynx over a malleable stylet. There were no complications such as coughing, gagging or bleeding. Capnographic confirmation of successful tracheal intubation was followed by the induction of anaesthesia with intravenous propofol. In the post anaesthetic care unit, she reported that she could recall the intubation process; however, it was not unpleasant. Discussion As visualisation of the glottis during videolaryngoscopy is not dependent on aligning the oral-pharyngeallaryngeal axes, there is less airway and cervical manipulation. This allows better patient tolerance and less cervical spine movements. These are obvious advantages in difficult airways or unstable cervical spines requiring awake intubations. The main drawbacks of flexible fiberoptic endoscopy for intubation are the steep learning curve and the increased time to intubation as compared with direct laryngoscopy. The advantage of videolaryngoscopy over fiberoptic endoscopy for intubation lies in its similarity to the conventional Macintosh laryngoscopy. It is easier to learn and use3. Intubation may be achieved in a shorter time–an important advantage considering that difficult airway situations sometimes occur in the most urgent and unexpected occasions. Most videolaryngoscopes are portable and fast to set up4. Supplemental oxygen can be given easily via a nasal cannula throughout the entire intubation process. Administration of supplemental oxygen is possible but more cumbersome when fiberoptic endoscopy is used for awake intubation. Awake videolaryngoscopy can also be used for assessment of suspected difficult airways5. This technique may spare the patient the discomfort of undergoing awake intubation. Ability to visualise the cords awake provides reassurance to the anaesthesiologist about being able to secure the airway after inducing general anaesthesia. McGrath® Mac improves the grade of laryngoscopic view whilst using a conventional laryngoscopy technique. It allows viewing * Corresponding author Email: thongszeying@gmail.com 1 Associate Consultant, Anaesthesia and Intensive Care, Singapore General Hospital, Singapore 2 Consultant, Anaesthesia and Intensive Care, Singapore General Hospital, Singapore 3 Associate Consultant, Anaesthesia and Intensive Care, Singapore General Hospital, Singapore An ae st he tic s & Cr iti ca l C ar e